It is known in the art to convert liquid nitrogen to gaseous nitrogen to treat and stimulate oil and gas wells. The converter must pump nitrogen to high pressures, such as 10,000 psi, and heat the liquid nitrogen to convert it to gas. However, the environment around oil and gas wells is frequently hazardous and, therefore, the use of open flames or high temperatures to convert the liquid to gas is dangerous.
U.S. Pat. Nos. 4,290,271, 4,197,712, 4,031,705 and 3,229,472 are directed to liquid to gas converters, the most notable being exemplified by U.S. Pat. No. 4,290,271 which is directed to a nitrogen liquid to gas converter which employs an air stream as the heat exchange medium, and U.S. Pat. No. 4,197,172 directed to vaporizing cryogenic fluids with engine heat where direct contact between the engine water line and the nitrogen line raises the potential problem of the engine water freezing. The invention presented herein represents an improvement over such patented inventions. The present invention is more efficient than a system employing an air stream and considerably lighter in weight and avoids the problem of engine water freeze-up which exists in the prior art.
The present invention is directed to a self- contained flameless nitrogen liquid to gas converter which pressurizes the nitrogen and converts it into a gaseous state for use in an oil and gas field environment. More particularly, the present invention is directed to a nitrogen liquid to gas converter employing a closed-loop water system providing for a use of waste heat rejected from engine and hydraulic systems to be used in vaporizing the liquid nitrogen.